Inhibiting actions is associated with the inferior
frontal gyrus (IFG) and is regulated by serotonin. Here we explore the link
between the serotonin receptor type 5-HT2A and activity in IFG during response
inhibition. 17 subjects performed a Go/No-Go task during fMRI, with treatments
to acutely increase (citalopram) or decrease (acute tryptophan depletion, ATD)
serotonin, or no treatment. We also used 18-F-altanserin positron emission
tomography to map 5-HT2A receptor binding. Individuals with low 5-HT2A had
greater activation of IFG after ATD. Individuals with high 5-HT2A had greater
activation after citalopram. Conclusion: effects of serotonergic treatments
depend on individual differences in 5-HT2A.